import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Long[] dp = new Long[81];
        dp[1] = 1L;
        dp[2] = 1L;
        for (int i = 3; i < dp.length; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            int b = in.nextInt();
            long sum = 0;
            for (int i = a; i <= b ; i++) {
                sum += dp[i];
            }
            System.out.println(sum);
        }
    }
}